ICD-10 Code K12.39 – Other oral mucositis (ulcerative) (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K12.39 – Other oral mucositis (ulcerative)
What it is
K12.39 identifies ulcerative inflammation of the oral mucosa that does not fit a more specific oral mucositis code. Use it for documented mouth ulceration or mucosal inflammation when the record supports this diagnosis.
Clinical signs
Clinical features may include painful oral sores, erythema, mucosal breakdown, and difficulty eating or speaking. Clinical features vary; refer to documentation.
When to use this code
Use K12.39 when the provider documents other oral mucositis with ulceration and no more specific oral diagnosis is stated. It may apply to nonspecific ulcerative inflammation of the mouth, especially when the note clearly distinguishes it from stomatitis or oral thrush. Check documentation if the cause is unclear.
Do not use for
Do not use this code for simple mouth pain, aphthous ulcers, or oral lesions with a different documented cause. If the chart identifies another specific oral condition, code that condition instead.
Coding tip
Confirm the provider’s wording includes ulcerative oral mucositis before assigning K12.39.